1. Field of the Invention
The present invention relates to a connection device connected to a network mounted on a boat, and a program executed by the connection device.
2. Description of the Related Art
Conventionally, when a connection device is connected to this type of network, it is necessary to prepare the connection device in conformity with a protocol (communication protocol) of the network. Therefore, in a case where there are plural types of protocols in the network, it is troublesome to have to prepare the same number of connection devices as number of protocols.
For a method to prevent this unnecessary complication, there have been proposed a technique disclosed in JP-U-Hei 5-59282 (hereinafter referred to as the related art 1) or a technique disclosed in JP-B-3669671 (hereinafter referred to as the related art 2).
However, the related art 1 has problems. First, it is necessary to determine a type of protocol every time that a failure diagnosis device is connected, so in a case of the device that is connected at all times, a waiting time for a complete determination is long and impractical. In addition, erroneous determination occurs more frequently, and sufficient reliability cannot be ensured.
Second, when the connection device conforming to a protocol that performs authentication (hereinafter referred to as an authentication conforming device) is connected to a network that uses a protocol that does not perform authentication (hereinafter referred to as an unauthenticated protocol), it may cause authentication failure. Therefore, upward compatibility is not ensured, and usability is decreased.
On the other hand, the related art 2 requires plural communication lines corresponding to a number of failure diagnosis circuits, making it impossible achieve a low-cost arrangement.